Pressure tubes are normally tubes that can take pressures higher than normal atmospheric pressure, normally up to several thousand times the atmospheric pressure. Such pressurised tubes are subject to strict safety regulations. A faulty tube ejecting high pressure fluid could cut of a limb of staff handling the tube. Tubes must be serviced, e.g. tested and inspected, according to regulations and can only be used for certain purposes, pressures, and time. It is desirable to provide a method to ensure correct and safe service and handling of a tube.
Currently tubes are marked with bar codes, colour labels, sheet metal, or plastic tags with stamped information. Such marking is typically an identification number, a product code, of the tube. It is a technical problem that such marking does not contain enough information and there is no international standard for such information. The information is limited to the physical size of the marked area. It is a technical problem to provide a marking that can be read in many different languages and areas of the world.
A further technical problem is that any marking should also fit and work together with already existing tubes. The marking should be part of the tube, but the cost of a marking is small in relation to the cost of the tube and any of its couplings. Therefore, it is desirable that the marking is not expensive to make. It is further a technical problem to avoid cumbersome arrangement and/or arrangements that are expensive to manufacture.
There is a desire to be able to provide a marking to a tube that can be read from the tube at different places along the tube. A marking is fixed to the tube at a certain position and that position may not be viewable because of the environment that the tube is in. For example, the part of the tube with the marking is inside a machine and therefore the marking can not be read.
The present invention is directed to overcoming one or more of the problems as set forth above.